
package com.myrule;

import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.AbstractLoadBalancerRule;
import com.netflix.loadbalancer.ILoadBalancer;
import com.netflix.loadbalancer.Server;

import java.util.List;
import java.util.concurrent.ThreadLocalRandom;

/**
 * A loadbalacing strategy that randomly distributes traffic amongst existing
 * servers.
 * 
 * @author stonse
 * 
 */
public class MyRandomRule extends AbstractLoadBalancerRule {

    /**
        每个服务，访问5次，换下一个服务（一共三个）
        total = 0; 默认=0，如果=5，我们指向下一个服务的节点
        index = 0；默认0，如果total=5，index+1，
     */

    private int total = 0;  //被调用的次数
    private int currentIndex = 0;   //当前是谁在提供服务

//    @edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "RCN_REDUNDANT_NULLCHECK_OF_NULL_VALUE")
    public Server choose(ILoadBalancer lb, Object key) {
        if (lb == null) {
            return null;
        }
        Server server = null;

        while (server == null) {
            if (Thread.interrupted()) {
                return null;
            }
            List<Server> upList = lb.getReachableServers();  //获得活着的服务
            List<Server> allList = lb.getAllServers();    //获得全部的服务

            int serverCount = allList.size();
            if (serverCount == 0) {
                return null;
            }

//            int index = chooseRandomInt(serverCount);    //生成区间随机数
//            server = upList.get(index);      //从活着的服务中随机获取一个

            //=====================================================

            if(total < 5){
                 server = upList.get(currentIndex);
                 total ++;
            }else{
                total = 0;
                currentIndex++;
                if (currentIndex >= upList.size()){
                    currentIndex = 0;
                }
                server = upList.get(currentIndex);      //从活着的服务中获取指定的服务来进行操作
            }

            //=====================================================

            if (server == null) {
                Thread.yield();
                continue;
            }

            if (server.isAlive()) {
                return (server);
            }

            server = null;
            Thread.yield();
        }

        return server;

    }

    protected int chooseRandomInt(int serverCount) {
        return ThreadLocalRandom.current().nextInt(serverCount);
    }

	@Override
	public Server choose(Object key) {
		return choose(getLoadBalancer(), key);
	}

	@Override
	public void initWithNiwsConfig(IClientConfig clientConfig) {
		// TODO Auto-generated method stub
		
	}
}
